Welcome to the Zaqar’s Documentation!

Zaqar is a multi-tenant cloud messaging and notification service for web
and mobile developers.

The service features a REST API, which developers can use to send messages
between various components of their SaaS and mobile applications, by using a
variety of communication patterns. Underlying this API is an efficient
messaging engine designed with scalability and security in mind. The Websocket
API is also available.

Other OpenStack components can integrate with Zaqar to surface events to end
users and to communicate with guest agents that run in the “over-cloud” layer.

Choice between two communication transports. Both with Keystone support:

Firewall-friendly, HTTP-based RESTful API. Many of today’s developers
prefer a more web-friendly HTTP API. They value the simplicity and
transparency of the protocol, it’s firewall-friendly nature, and it’s huge
ecosystem of tools, load balancers and proxies. In addition, cloud
operators appreciate the scalability aspects of the REST architectural
style.

Websocket-based API for persistent connections. Websocket protocol
provides communication over persistent connections. Unlike HTTP, where
new connections are opened for each request/response pair, Websocket can
transfer multiple requests/responses over single TCP connection. It saves
much network traffic and minimizes delays.

Multi-tenant queues based on Keystone project IDs.

Support for several common patterns including event broadcasting, task
distribution, and point-to-point messaging.

Component-based architecture with support for custom backends and message
filters.

Efficient reference implementation with an eye toward low latency and high
throughput (dependent on backend).

Highly-available and horizontally scalable.

Support for subscriptions to queues. Several notification types are
available:

The Zaqar API is data-oriented. That is, it does not provision message brokers
and expose those directly to clients. Instead, the API acts as a bridge between
the client and one or more backends. A provisioning service for message
brokers, however useful, serves a somewhat different market from what Zaqar is
targeting today. With that in mind, if users are interested in a broker
provisioning service, the community should consider starting a new project to
address that need.